THE CELL

Basic Unit of LifeCell Song

Principles of Cell Theory1. Cells are basic units of life2. Biogenesis - All Cells arise from other cells3. Energy flow (metabolism & biochemistry)

of life occurs within cells. 4.. All organisms are made of one or

more cells• Prokaryotic = 1 cell (Unicellular)• Eukaryotic = 2 or more cells (Multicellular)

Cell Theory

Bacteria

ENDOSYMBIOTIC THEORY

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Double Membranes

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Surface Area to Volume Ratio

• The most efficient cells are the smallest

• Small cells have a GREATER surface area to volume ratio

What is the Surface Area to Volume Ratio?

Cellular Machinery

Close-up of nuclearenvelope

Nucleus

Nucleolus

Chromatin

Nuclear envelope:Inner membraneOuter membrane

Nuclear pore

Porecomplex

Ribosome

Pore complexes (TEM) Nuclear lamina (TEM)

1 µm

Rough ER

Nucleus1 µm

0.25 µm

Surface of nuclear envelope

Nucleus &

Nucleolus

LE 6-11

Ribosomes

0.5 µm

ER Cytosol

Endoplasmicreticulum (ER)

Free ribosomes

Bound ribosomes

Largesubunit

Smallsubunit

Diagram ofa ribosome

TEM showing ERand ribosomes

Ribosomes

LE 6-12

Ribosomes

Smooth ER

Rough ER

ER lumenCisternae

Transport vesicle

Smooth ER Rough ER

Transitional ER

200 nm

Nuclearenvelope

EndoplasmicReticulum

LE 6-13

trans face(“shipping” side ofGolgi apparatus) TEM of Golgi apparatus

0.1 µm

Golgi apparatus

cis face(“receiving” side ofGolgi apparatus)

Vesicles coalesce toform new cis Golgi cisternae Vesicles also

transport certainproteins back to ER

Vesicles movefrom ER to Golgi

Vesicles transport specificproteins backward to newerGolgi cisternae

Cisternalmaturation:Golgi cisternaemove in a cis-to-transdirection

Vesicles form andleave Golgi, carryingspecific proteins toother locations or tothe plasma mem-brane for secretion

Cisternae

Golgi Apparatus

Phagocytosis: lysosome digesting food

1 µm

Plasmamembrane

Food vacuole

Lysosome

Nucleus

Digestiveenzymes

Digestion

Lysosome

Lysosome containsactive hydrolyticenzymes

Food vacuolefuses withlysosome

Hydrolyticenzymes digestfood particles

Vacuoles

LE 6-15

5 µm

Central vacuole

Cytosol

Tonoplast

Central vacuole

Nucleus

Cell wall

Chloroplast

Central Vacuoles

(Plants Only)

LE 6-16-1

Nuclear envelope

Nucleus

Rough ER

Smooth ER

LE 6-16-2

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi

LE 6-16-3

Nuclear envelope

Nucleus

Rough ER

Smooth ER

Transport vesicle

cis Golgi

trans Golgi

Plasma membrane

LE 6-19

Chloroplast

Peroxisome

Mitochondrion

1 µm

Peroxisomes

LE 6-17

Mitochondrion

Intermembrane space

Outer membrane

Inner membrane

Cristae

Matrix

100 nmMitochondrialDNA

Freeribosomes in themitochondrialmatrix

Mitochondria

LE 6-18

Chloroplast

ChloroplastDNA

RibosomesStroma

Inner and outermembranes

Granum

Thylakoid1 µm

Chloroplasts

Cytoskeleton• The cytoskeleton is a network of fibers

extending throughout the cytoplasm• It organizes the cell’s structures and

activities, anchoring many organelles• It is composed of three types of

molecular structures:–Microtubules–Microfilaments– Intermediate filaments

LE 6-21a

Vesicle

Receptor formotor protein

Microtubuleof cytoskeleton

Motor protein(ATP powered)

ATP

LE 6-21b

0.25 µmMicrotubule Vesicles

LE 6-28Centralvacuole of cell

PlasmamembraneSecondarycell wall

Primarycell wall

Middlelamella

1 µm

Centralvacuole of cell

Central vacuoleCytosol

Plasma membrane

Plant cell walls

Plasmodesmata

Cell Wall

LE 6-23a

5 µm

Direction of swimming

Motion of flagella

Flagella

LE 6-23b

15 µm

Direction of organism’s movement

Motion of cilia

Direction ofactive stroke

Direction ofrecovery stroke

Cilia

LE 6-25b

Wavelike motion

Cross-linkingproteins insideouter doublets

ATP

Anchoragein cell

Effect of cross-linking proteins

LE 6-29a

EXTRACELLULAR FLUID ProteoglycancomplexCollagen

fiber

Fibronectin

Integrin Micro-filaments

CYTOPLASM

Plasmamembrane

Extracellular Matrix

Tight junctions preventfluid from moving across a layer of cells

Tight junction

0.5 µm

1 µm

0.1 µm

Gap junctionExtracellularmatrix

Spacebetweencells

Plasma membranesof adjacent cells

Intermediatefilaments

Tight junction

Desmosome

Gapjunctions

Intracellular Junctions

LE 6-8

Hydrophilicregion

Hydrophobicregion

Carbohydrate side chain

Structure of the plasma membrane

Hydrophilicregion

Phospholipid Proteins

Outside of cell

Inside of cell 0.1 µm

TEM of a plasma membrane

Plasma Membrane

0.25 µm

Microtubule

Centrosome

Centrioles

Longitudinal sectionof one centriole

Microtubules Cross sectionof the other centriole

Centrioles